The goal of this research is to develop a fluorescence in situ hybridization (FISH) assay for the detection of the t(14;18)(q32;q21) chromosomal translocation encountered in approximately 60% of B-cell lymphomas. These tumors are treated by chemotherapy and bone marrow transplantation; however, many patients relapse and become refractory to treatment. Diagnosis and post-treatment follow-up are performed by karyotype, Southern blotting, or PCR each of which has limitations of specificity and/or sensitivity. Therefore, another precise, reliable, and easy method to detect tumor cells, especially in the post-treatment set up is needed. Such a method is FISH. Unfortunately, no clinically tested probes are available for the detection of t(14;18) by FISH. In this Phase I application, we propose to develop a novel approach to unambiguously identify translocation carrying nuclei in diagnostic and follow-up patient samples. PROPOSED COMMERCIAL APPLICATION: The proposed research will provide a FISH assay to detect the t(14;18)(q32;q21) chromosomal translocation encountered in the majority of B-cell non-Hodgkin's lymphomas for use in cancer cytogenetic reference laboratories.